A backlight module comprises a light guide and a light source. The light source, located at a side of the light guide, emits light to travel through the light guide. The light guide is used for guiding the light so as to enhance the brightness of the display panel and make the image display uniformly.
In order to reduce a thickness of a tablet computer, a laptop computer or a display panel, the light guide of the backlight module thereof is thinned down in recent years in order to satisfy the demand for consumers. However, when the thickness of the light guide is reduced, the dimension of a light inputting surface of the light guide is smaller than that of a light emitting surface of the light source. In other words, the light inputting surface of the light guide cannot completely correspond to the light emitting surface of the light source, which leaks a part of the light from the light source, thereby decreasing the efficiency of illumination. Hence, the problem of the light leak between the light source and the thinned-down light guide needs to be solved by manufacturers in order to enhance the efficiency and the uniformity of the illumination of the backlight module.